Process of coating glass with a titanium polymer and article produced thereby



United States Patent:

PROCESS 0F COATING GLASS WITH A TITANIUM POLYNIER AND ARTICLE PRODUCEDTHEREBY Thomas Boyd, Springfield, and Robert 1V1. Dickey, NorthWilbraham, Mass, assignors to Monsanto Chemical Company, St. Louis, Mo.,a corporation of Delaware No Drawing. Application June 17, 1950, SerialNo. 168,853

13 Claims. (Cl. 117-124) This invention relates to coated glasssurfaces. More particularly, the invention relates to glass surfacescarrying a coating of a condensation polymer of an organo titaniumcompound.

It is trequentl desirable to coat glass articles such as fibers,filaments, bats, fabrics, sheets, Windshields, lenses, etc. to changethe surface characteristics of the glass. For some purposes, thecoatings should act as lubricants; for others as a non-fogging agent;for still others as a non-reflecting surface, etc. The coatings shouldbe resistant to chemical media and to heat and should be easy to apply.Many coating materials have been suggested, most of which are deficientin one or more of the critical features desired.

One object of this invention is to provide a coated giass surface.

A further object is to provide a coated glass which is non-wettablc byaqueous media.

Another object is to provide a coated glass which is non-reflecting.

Still another object is to provide temperature and v chemical resistantsized glass fabrics and bats.

A still further object is to provide glass coated with astrongly-adherent, water-insensitive polymeric coating dc rived from astraight-chain polymer of a tetraorgano derivative of orthotitanic acid.

These and other objects are attained by coating a glass surface with ananhydrous organic solvent solution of straight-chain polymer of atetraorgauo derivative of orthotitanic acid, removing the solvent andreacting the straight-chain polymer with water to thereby form apolymeric. strongly-adherent, water-insensitive coating on the glasssurface.

The following examples are given in illustration and are not intended aslimitations on this invention. Where parts are mentioned, they are partsby weight.

Example I A glass filament is prepared by the conventional procass offorcing molten glass through a small orifice into cool air. Thefilament, being of relatively small diameter, is soon cooled to aboutroom temperature. Thereafter, the filament is passed through a toluenesolution of a polymer of tetrabutyl ortho titanate containing about l%polymer by weight. The speed of the coatlug operation is governed so asto deposit on the glass :1 film of polymer about 0.1 mil thick. Thecoated filament is then passed through a humid atmosphere at roomtemperature (Xi- C.). The resultant coated filament is not wetted bywater or other aqueous media. The coating is nearly as hard as the glassbut is still flexible enough so that the glass filament can be woven orprepared into giass mats without disrupting the coating. On testing thetensile strength of the coated filament and compuringthe results withtests made on the uncoated filament, it is found that there issubstantially no change.

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Example II A glass filament is passed through an xylol solution ofpolymeric tetrastearyl ortho titanate containing about 1% of the polymerby weight at such a rate as to pick up a coating about 1.0 mil thick.The coated filament is subjected briefly to a humid atmosphere at roomtemperature and men examined for tensile strength and wen-ability. Thefilament is not wetted by aqueous media and retains substantially all ofthe tensile strength of the original glass filament. It is further notedin this case that the filament has a waxy feel and slides over adjacentglass surfaces bearing the same type of coating without the developmentof frictional heat. In other words, this coating has the additionaladvantage that it has lubricating properties. Furthermore, the coatingwas resistant to elevated temperatures up to the softening point of theglass.

Example III A pane of glass is thoroughly cleaned and then dipped intoan xylol solution of polymeric tetrabutyl ortho titanate containingabout 0.001% by weight of the polymer. Excess solution is allowed todrain from the surface which is then exposed to a humid atmosphere. Theresultant coated glass is not wetted by aqueous media and the surfacesthereof are substantially nonreflecting. The coated glass may be used asa window pane or it may be laminated with another coated pane of glassand a polyvinyl acetal resin to provide laminated glass for automobileWindshields. Laminated glass thus made shows greater adhesion to theplastic interlayer than when uncoated glass is used.

Example IV An automobile windshield ls spray-coated with an extremelythin coating of a polymeric tetrabutyl ortho titanate using a 0.0001%solution of the polymer in Xylolbutanol solvent. As soon as the solventevaporates the polymer coating is subjected to a stream of humid air forabout one minute. A hard, transparent, tough coating about 5.0 micronsthick is obtained which cuts down the reflection from the glass surfacesby more than 50%. Windshields thus coated reduce the eyestrain ofdriving since glare from reflection of light from the Windshieldsurfaces is greatly reduced.

The coatings of this invention are condensation polymers of organicderivatives of titanium which are described and claimed in copendingapplication Serial No. 122,844 filed October 21, 1949, now abandoned.

The polymers there described are prepared by reacting 0.5 to 1.5 mols ofWater with 1 mol of a tetraorgano derivative of orthotitanic acid atroom temperature in an otherwise anhydrous inertorganic solvent such asan aromatic or aliphatic hydrocarbon or a halogenated hydrocarbon. Thus,for example, as is shown in Examplel or" S. N. 122,844, whentetra-n-butyl orthotitanate is dissolved in anhydrous butanol and about0.9 mol of water per mol of. orthotitanate is added thereto and theresultant solution is maintained at about 30 C. for 24 hours, there isobtained on vacuum distillation of the solvent a residual transparentliquid polymeric product having a viscosity of about 5-25 poises.

The polymers prepared by the process describ d in the aforesaidapplication S. N. 122,844 range from liquids to hard solids depending onthe starting derivative of orthotitanic acid and the amount of waterused. In general, ii 0.5 mol of water is used, the product isessentially a dimer. As more water is used, longer straightchainpolymers are formed until the amount of water becomes greater than 1 molper mol of orthotitanic derivative. At this point a substantial amountof crosslinking takes place, the viscosity of the polymers risesabruptly and the majority of the resulting polymers are solids. Thepolymers to be used as starting materials in accordance with the presentinvention are the straightchain polymers of tetraorgano derivatives oforthotitanic acid prepared by reacting each rnol of the tetraorganoderivative with 0.5-1 mol of water. The straight-chain polymers arecrosslinked by further reaction with water.

The preferred polymers are polymers of saturated alkyl esters of orthotitanic acid such as the tetramethyl, ethyl, butyl, isobutyl, pentyl,octyl, lauryl, cetyl, stearyl, etc. esters. Unsaturated esters such asvinyl, allyl and methallyl esters may be used also. It is also possibleto employ the mixed anhydrides of ortho titanic acid with mono orpolybasic acids such as titanium tetraphthalate, titanium tetraacetate,etc. and the amides of ortho titanic acid such as the tetrabutyl amideof ortho titanic acid. The polymerization process is to be distinguishedfrom polymerization through the instrumentality of unsaturated groupssuch as allyl, vinyl, acetylenic, etc. groups since the polymers arecondensation products and are not addition polymers such as are producedby polymerization through unsaturated groups.

The coatings must be applied from substantially anhydrous organicsolvent solutions. The solvents may be alcohols, hydrocarbons, orchlorinated hydrocarbons, or

mixtures of these. Generally, it is preferable to use the solvent inwhich the polymer is prepared as the medium for application of thepolymer as a coating. For practical and economical reasons, acombination of two or more solvents may be desirable.

After the coating is applied to the glass, the solvent is allowed toevaporate and thereafter the polymer is subjected to water or a moistatmosphere for a short time, which may vary according to the thicknessof the coatmg. sufficient to harden the coating and set it in itspermanent form.

The amount of polymer applied to the glass depends somewhat on the enduse of the glass. For glass fibers and filaments, it is desirable tohave a coating of 0.0l2.0 mils thickness. Where the main purpose of thecoating is to reduce reflectance from the glass surfaces, the coatingshould be 1-10 microns in thickness.

The titanium polymers of this invention range from crystal clear tosolid white in color, from extremely hard to soft and waxy in texture.They are strongly adherent to glass and the majority of them cannot beremoved from the glass by any means except abrasive action. After beingset by the action of water, the coatings are impervious to andnon-wettable by water and aqueous media. They are not attacked byalkaline or acid media, and are unaffected by organic solvents. They arenot decomposed at elevated temperatures. The waxy polymers tend tolubricate the glass; a property which is especially desirable in thesizing of glass yarns and filaments, bats and fabrics.

Glass bats and fabrics sized with thetitanium condensation polymers areparticularly valuable since the size is resistant to temperature as wellas to chemical reagents. Thus, titanium polymer-sized glass bats andfabrics may be used as table mats, ironing board covers, etc. withoutdanger that hot objects placed thereon will decompose the size, causingdiscoloration.

The coatings of this invention are advantageous for the sizing of glassfilaments and yarns and for the treat ment of other glass surfaces toreduce reflection of light therefrom and to render the surfacesnon-wettable by water. They may be used in automobile Windshields tosubstantially reduce glare without reducing the light transmission ofthe glass. They may be used to coat lenses for use in cameras,binoculars, telescopes and Normally exposures of from one to fiveminutes are other optical instruments to reduce interference with theoptical properties of the glass by surface reflectance. They may be usedto coat store windows to reduce reflections so that the merchandisedisplayed behind the glass front will be more attractively set out. Theymay be used to coat spectacle lenses to substantially reduce the foggingof the lenses due to atmospheric moisture.

The coatings of organo titanium condensation polymers may also beapplied to decorative glass articles and to glass blocks and to othervitreous materials. By reducing reflection from decorative articles, thebeauty thereof is greatly enhanced.

It is obvious that many variations may be made in the products andprocesses of this invention without departing from the spirit and scopethereof as defined in the appended claims.

What is claimed is:

1. Glass carrying on the surface thereof a continuous transparentstrongly adherent pigment-free water-insensi tive coating comprising thepolymeric condensation prod net of water and a straight-chain polymer ofa tetraorgano derivative of orthotitanic acid.

2. A process for coating glass which comprises coating glass with asubstantially anhydrous pigment-free organic solvent solution of astraight-chain polymer of a tetraorgano derivative of orthotitanic acid,evaporating the solvent and reacting the polymer with water to form acontinuous transparent strongly-adherent water-insensitive coating onthe glass.

3. Glass as in claim 1 wherein the glass is in the form of a filament.

4. Glass as in claim 1 wherein the glass is in the for: of a sheet.

5. Glass as in claim 1 wherein the tetraorgano derivative is a saturatedalkyl derivative of orthotitanic acid.

6. Glass as in claim 5 wherein the saturated alkyl derivative oforthotitanic acid is tetrabutyl orthotitanate.

7. Glass as in claim 1 wherein the tetraorgano derivative istetrastearyl orthotitanate.

8. Glass as in claim 1 wherein the tetraorgano derivative is a mixedanhydride of orthotitanic acid and an organic acid.

9. Glass as in claim 1 wherein the tetraorgano derivative is a tetraamide of orthotitanic acid.

1.0. A process as in claim 2 wherein the glass is coated by being passedthrough the polymer-containing solvent solution.

ll. A process as in claim 2 wherein the glass is coated by being dippedinto the polymer-containing solvent solution.

12. A process as in claim 2 wherein the glass is coated by being sprayedwith the polymer-containing solvent solution.

13. A process as in claim 2 wherein the polymer is reacted with water byexposure to a humid atmosphere.

References Cited in the file of this patent UNITED STATES PATENTS2,466,642 Larsen Apr. 5, i949 2,530,635 Sowa Nov. 21, I950 FOREIGNPATENTS l25,450 Australia Sept. l2, 1947 OTHER REFERENCES Ellis, TheChemistry of Synthetic Resins, vol. 2, i935, Reinhold Pub. Corp, NewYork City, N. Y. Pg. 1239.

Journal Oil & Colour Chemists Assn, vol. 31, No. 340, 1948, pp. 405-410.

Esters of Titanium by Kraitzer, K. McTaggart and G. Winter. i

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2. A PROCESS FOR COATING GLASS WHICH COATING GLASS WITH A SUBSTANTIALLYANHYDROUS PIGMENT-FREE ORGANIC SOLVENT SOLUTION OF A STRAIGHT-CHAINPOLYMER OF A TETRAORGANIC DERIVATIVE OF ORTHOTITANIC ACID, EVAPORATINGTHE SOLVENT AND REACTING THE POLYMER WITH WATER TO FORM A CONTINUOUSTRANSPARENT STRONGLY-ADHERENT WATER-INSENSITIVE COATING ON THE GLASS.